Method and apparatus for controlling the manufacture of synthetic fibers

ABSTRACT

Disclosed is a method of controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the tow is moved through a water bath, drafted, and subsequently moved through a heatsetting chamber wherein the tow is heatset, the method of controlling the processing comprising A. sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers, B. comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and C. responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature. In a preferred embodiment a thermocouple is used to sense the temperature of the fibers leaving the heatsetting chamber and water is removed from the wet fibers entering the heatsetting chamber by positioning a horizontally extending jet body member at the downstream exit from the water bath, then guiding the two from the water bath to that portion of the surface of the jet body member wherein there is located an opening through which air is blown and then removing water from the fibers by blowing air through the opening. This invention is particularly applicable to the manufacture of high tenacity poly(ethylene terephthalate).

Mates lFinley et al.

atent [1 1 METHOD AND APPARATUS FOR CONTROLLING THE MANUFACTURE 01F SYNTHETIC FIBERS [75] Inventors: Donald L. Finley; Edward A.

Morehead, both of Kingsport, Tenn.

[7 3] Assignee: Eastman Kodak Company,

Rochester, N.Y.

[22] Filed: Dec. 27, 1972 [21] Appl. No.: 319,103

Related US. Application Data [63] Continuation-in-part of Ser. No. 257,406, May 26,

[52] US. Cl 34/34, 34/54, 68/20, 19/66 T, 28/71.3 [51] Int. Cl. F26h 5/00 [58] Field of Search 68/19.1, 20; 19/66 T; 28/75 R, 71.3; 34/12, 23, 34, 70, 115, 122, 130, 156, 160, 54

[56] References Cited UNITED STATES PATENTS 3,625,812 12/1971 Gudaz et a1 34/54 X 3,481,012 12/1969 Sazon 28/7l.3 3,367,041 2/1968 Troope et al. 34/54 3,286,307 11/1966 Watson 19/66T 3,203,678 8/1965 Sawyer et a1 34/54 UX 2,177,323 10/1939 Kirkendall 68/20 X Primary Examiner.Wi1liam F. ODea Assistant Examiner-W. C. Anderson Att0rneyChar1es R. Martin F DRAFTING ZONE u Q I DRAFTING WATER H0 ll zone BATH STEAM TUBE 4 OVEN 1 PNEUMATIC CONVERTER M ELECTRICAL [5 7 ABSTRACT Disclosed is a method of controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the tow is moved through a water bath, drafted, and subsequently moved through a heatsetting chamber wherein the tow is heatset, the method of controlling the processing comprising A. sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers,

B. comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and

C. responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature.

In a preferred embodiment a thermocouple is used to sense the temperature of the fibers leaving the heatsetting chamber and water is removed from the wet fibers entering the heatsetting chamber by positioning a horizontally extending jet body member at the downstream exit from the water bath, then guiding the two from the water bath to that portion of the surface of the jet body member wherein there is located an opening through which air is blown and then removing water from the fibers by blowing air through the open ing. This invention is particularly applicable to the manufacture of high tenacity poly(ethy lene terephthalate).

11 Claims, 14 Drawing Figures RECORDER 191 O COMPARATOR AMPERAGE PATENTEBJAM 15 mm SHEET 10E 8 FIBER (TEMPERATURE) PMENTEII WI 15 19A SHEET 7 [IF 8 EFFECT OF TOW DISPLACEMENT ON JET DEVICE WATER REMOVAL IN TERMS OF TEMPERATURE fj g. 12

5 O 5 w m m 6L mmDhqmmmimt.

TOW DISPLACEMENT (INCHES) 0 0000 wm6w432 E R U S S E R P H AIR FLOW wEmdv 304m E3 TOW DISPLACEMENTUNCHESI EFFECT OF TOW DISPLACEMENT BY JET DEVICE ON AIR FLOW RATES AND AIR PRESSURE METHOD AND APPARATUS FOR CONTROLLING THE MANUFA'CTURE OF SYNTHETIC FIBERS This application is a continuation-in-part of our copending application Ser. No. 257,406, filed May 26,

1972, entitled Improved Method for Removing Water from Tow and an Improved Dewatering Jet for Practicing the Method.

This invention relates to a method and apparatus for controlling a process for the manufacture of a continuous length tow of synthetic fibers wherein the tow is moved through a water bath, drafted, and then the wet drafted tow is moved into a heatsetting chamber wherein it is heatset. This invention comprises sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers, comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and, responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature.

Achieving uniform dye take up in synthetic fibers is one of the more difficult quality control problems experienced in the manufacture of synthetic fibers. Customers of fibers manufactuers demand that all fibers of a given type purchased from one manufacturer exhibit a comparable dye take up. The customers of the fiber manufacturer make this demand so that they can establish a uniform manufacturing process to make useful articles from the fiber and not have to continually make adjustments to their manufacturing process necessitated by differences in dye take up in the'fibers. Thus, only very slight variations in dye take up within a single shipment, or between different shipments, is regarded as acceptable by customers of the fiber manufacturer.

The dye take up of many synthetic fibers, including high tenacity poly(ethylene terephthalate) fibers, is inversely proportional to the temperature the fibers ultimately achieve in the heatsetting chamber.

Referring now to FIG. 1 there is illustrated a correlation between dye take up of high tenacity poly(ethylene terephthalate) fibers and the sensed temperature of the fibers leaving the heatsetting chamber. In FIG. 1 the dye take up values are determined by standard laboratory methods and the relative temperature values are determined by measuring the temperature of the fibers leaving the heatsetting chamber by use of an lrcon CI-I-34 Infrared Radiation Thermometer manufactured by lrcon Inc., Niles, Ill. To develop these data eleven runs are made and numerous values for dye take up and sensed fiber temperature are determined during each of the eleven runs. Each different kind of symbol represents the values determined during each of the eleven runs. After the data are plotted a dye take up value of zero'is arbitrarily established. Thus, data plotted above the zero line represents too little dye take up and data plotted below the zero line represents too much dye take up. The data points of FIG. 1 are then mathematically correlated into a linear approximation by use of a least squares analysis. Thus the straight line passing through the array of data represents a linear correlation for dye take up versus the temperature of the fibers leaving the heatsetting chamber.

Since it is necessary to control dye take up of the fibers to assure uniformity, and further since there is a correlation between dye take up and the temperature of the fibers leaving the heatsetting chamber, then the dye take up of the fibers can be controlled by controlling the temperature of the fibers leaving the heatsetting chamber.

The temperature of the fibers leaving the heatsetting chamber might possibly be controlled in several ways. One method might be to alter the speed of the tow moving through the manufacturing process, but use of this method in a commercial operation would probably be undesirable because of the numerous adjustments required for a change in tow speed. Another method might be to vary the temperature of the heatsetting chamber, but use of this method would probably also be undesirable since the thermal inertia of the oven would create undesirable control problems. Thus, it is disenable that any method used to control dye take up of the fibers allow the manufacturing process to operate at steady state conditions while the control method is being used.

We have now discovered a process to control the dye take up of the fibers and still allow the manufacturing process to operate at steady state conditions.

An appreciation of our invention can be readily obtained by consideration in some detail the manner in which many kinds of synthetic textile fibers are manufactured.

In the manufacture of many kinds of textile fibers a continuous length tow of synthetic fibers is transported through various processing steps such as contacting the tow with water, heating the tow, drafting the tow, heatsetting the tow, and crimping the tow. Of course, the specific processing steps used, as well as the conditions used in each processing step, depend upon the properties that one desires to impart to the fibers.

The heatsetting step in particular is often used to impart certain desires properties to fibers of the tow. For instance, it is well known in the art that polyester fibers of moderate tenacity can be manufactured by conducting the heatsetting step under free shrink conditions. Also it is well known in the art that high tenacity polyester fibers, such as poly(ethylene terephthalate) fibers, can be manufactured by conducting the heatsetting step at constant length and at a temperature above the boiling point of water. Representative of this art relating to production of high tenacity polyester fibers using constant length heatsetting is U. S. Pat. No. 3,044,250, and U. S. Pat. No. 3,500,553.

Since the manufacture of high tenacity polyester fibers typically includes treatment in a water bath at some stage prior to heatsetting at constant length, the polyester fibers must be brought up to the heatsetting temperature, which is well above the boiling point of water, as the fibers pass through the heatsetting chamber. The mechanism involved in increasing the temperature of the wet fibers in the heatsetting chamber can be understood by considering the thermodynamics of heating a wet fiber to a temperature above the boiling point of water. As the wet fibers enter the heatsetting chamber the temperature of the fibers increase to the boiling point of water and remain at the boiling point of water until all the water boils or evaporates off the fibers. After all the water has been removed from the fibers and the fibers are bone-dry, then the temperature of the fibers starts to increase from the temperature of boiling water, and the temperature continues to increase throughout the time the fibersrernain in the heatsetting chamber. Thus, assuming the tow is moving through the heatsetting chamber at a constant rate, and further assuming that the heat transfer conditions within the heatsetting chamber remain constant, then the amount of water on the surface of the fibers entering the heatsetting chamber determines the final temperature the fibers ultimately achieve in the heatsetting chamber. Since the fibers entering the heatsetting chamber already have excessive water on their surface from treatment in the water bath, the amount of water that is removed from the fibers is related to the temperature the fibers ultimately achieve in the heatsetting chamber.

Numerous devices are known in the art that can be used to remove a portion of the water from the surface of the fibers before the fibers enter the heatsetting chamber. Examples of such devices are disclosed in U. S. Pat. No. 3,481,012 and U. S. Pat. No. 3,199,214. Another desirable device is disclosed in Ser. No. 257,406 filed May 26, 1972, entitled Improved Method for Removing Water from Tow and An Improved Dewatering .let Device for Practicing the Method."

In summary this invention comprises a method of controlling the processing ofa continuous length of tow of synthetic fibers wherein the fibers are contacted with water, drafted and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the wet drafted fibers are heatset at constant length by heating the wet drafted fibers to a ultimate temperature which is inversely proportional to the amount of water on the wet fibers entering the heatsetting chamber. Broadly, the method of this invention can be described as a method for controlling the dye take up of the fibers by controlling the heatsetting temperature of the fibers through control of the amount of water on the wet drafted fibers entering the heatsetting chamber, the actual method broadly comprising the steps of A. sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers,

B. comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and

C. responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature.

In one specific aspect of this invention, the temperature of the fibers leaving the heatsetting chamber is sensed with a thermocouple which generates a first signal which is an electrical signal having a voltage reflective of the magnitude of the sensed temperature. The first electrical signal can then be converted into a second electrical signal having an amperage reflective of the magnitude of the sensed temperature. The amperage of the second electrical signal is then compared with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and a third electrical signal having an amperage reflective of the magnitude of the result of the comparison is generated. The third electrical signal is then converted into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber. Responsive to the pneumatic signal, water is removed from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature.

In one other specific aspect of this invention, water is removed from the wet fibers by positioning a horizontally extending jet body member at the downstream exit from and above the heated water bath and subsequently guiding the tow upon exit of the tow from the heated water bath immediately to and displacing it nder and wrapping it party around that portion of the surface of the jet body member wherein there is located an opening through which air is blown. Water is removed from the fibers by blowing air through the opening against the wrapped around portion of the tow and toward the upstream portion of the tow and through the tow so that most of the water is primarily blown toward the upstream side of the tow while some water is blown through the tow in return to the heated water blath.

This invention can be further understood by considering FIG. 2 which is a schematic drawing of one specific embodiment of the invention.

Referring now to FIG. 2 there is illustrated a portion of a manufacturing process well known in the art for preparation of high tenacity poly(ethylene terephthalate) fibers. In the illustrated portion of the process a tow band 10 from a melt spinning operation (not shown) passes through a first set of drafter rolls in drafting zone 11, through a water bath 12, and then into a second set of drafter rolls in drafting zone 13. Following these stages the tow band 10 passes through a stream tube 14 in which it is brought to a predetermined temperature in preparation for passing through still another set of drafter rolls in drafting zone 15 prior to entering heatsetting chamber 16. The tow band 10, upon being heatset to a stabilized condition in heatsetting chamber 16, passes on to other processing operations including crimping and packaging. The portion of the process described above is disclosed in detail in U. S. Pat. No. 3,500,553.

As the tow band 10 exits from water bath 12 the fibers of the tow have water on their surface. Subsequent processing, including passage through steam tube 14, fails to remove the water from the surface of the fibers and consequently the fibers of tow 10 have water on their surface as they enter heatsetting chamber 16.

Since the fibers must be raised to a temperature in the order of 200C. in heatsetting chamber 16, the water on the surface of the fibers must be removed by evaporation or drying in the heatsetting chamber before the temperatures of the fibers can be increased to the required level.

Since the temperature that the fibers ultimately achieve in heatsetting oven 16 is related to the dye take up and the amount of water on the fibers entering heatsetting chamber 16 is related to the temperature the fibers ultimately achieve in heatsetting chamber 16, then control of the amount of water on the fibers entering the heatsetting chamber 16 can be used to control the dye take up of the fibers.

Referring still to FIG. 2, and concentrating now upon one specific embodiment of this invention, there is illustrated thermocouple means 101 to sense the temperature of the fibers leaving the heatsetting chamber and generate a first electrical signal having a voltage reflective of the magnitude of the sensed temperature. In the specific embodiment illustrated in FIG. 2 thermocouple means 101 can comprise a device employing a plurality of thermocouples.

Referring now to FIGS. 3 and 4 there is illustrated thermocouple means 101. Thermocouple means 101 comprises metal body A, supported by metal legs B. Body A contains passageway C having a cross section of that of a portion of a circle. Insulation D resides in passageway C. In the embodiment of FIGS. 3 and 4 insulation D is a portion of a TEFLON tube positioned coaxially with passageway C. Residing within insulation D, and positioned coaxially with insulation D and passageway C, is copper tubular member E having the torn hand Friding thereon. Copper is a particularly desirable material for tubular member E because of its high thermal conductivity. Tubular member E has a protective coating G in the location where the tow contacts member E. Chromium oxide is a particularly desirable coating due to its capability to protect the tow from damaging member E, which in turn causes member E to damage the tow.

Four Thermocouples H reside within the annulus of member E. Thermocouples H are of conventional construction and are well known in the art.

In operation, heat from tow F is conducted through member E and sensed by each of the four thermocouples H. Each thermocouple generates an electrical signal having a voltage reflective of the magnitute of the sensed temperature. The voltage output of each of the four thermocouples is added to form a voltage signal reflective of the magnitude of the sensed temperature of the tow.

Other means to sense the temperature ofthe fibers leaving the heatsetting chamber are fully within the scope of this invention.

One such device suitable for sensing the temperature of the fibers leaving the heatsetting chamber is an lrcon CH-34 Infrared Radiation Thermometer manufactured by lrcon Inc. of Niles, III. This device is a commercial available instrument that is specifically designed to measure temperatures of thin films of polymers exhibiting the fundamental absorption band of the carbonhydrogen bond. This instrument can be mounted at an oblique angle to the plane of the tow so that the field of view is an ellipse with the major axis approximately perpendicular to the line of travel of the tow. Used in this manner, the lrcon Infrared Radiation Thermometer produces an average temperature value but tells nothing about variability of temperature across the tow band. This instrument can also be mounted on a traversing device so that its field of view is perpendicular to the plane of the tow. By traversing the instrument temperature variability as well as average temperature can be obtained.

Another device suitable for sensing the temperature of the fibers leaving the heatsetting chamber is a Barnes Model T-6 Infrared Camera distributed by Barnes Engineering Company of Stanford, Conn. This device can be used in a manner similar to the lrcon Infrared Radiation Thermometer, but because of a focusing feature can be used to produce a thermal profile across the width of the tow band.

Referring again to FIG. 2 there is indicated means 102 to convert the first electrical signal having a voltage reflective of the magnitude of other sensed temperative of the fibers into a second electrical signal having an amperage reflective of the magnitude of the sensed temperature of the tow. In the embodiment of the invention of FIG. I means 102 comprises a Model 31- KX-U voltage to amperage converter manufactured by Acromag Inc., Wixom, Mich. Means 102 can be omitted in other embodiments of this invention.

Still referring to FIG. 2, there is indicated comparer means 103 to compare the amperage of the second electrical signal with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and generate a third electrical signal having an amperage reflective of the magnitude of the result of the comparison. In the embodiment of FIG. 2 means 103 can comprise a Catalogue Number 50-540017 J AMA Z c onffoller maniifactfirll 's'yonear Electric Company. Other conventional means well known in the art can be used.

A recorder 104 can be attached to comparer 103 if desired.

Continuing with FIG. 2, there is illustrated a means to remove water from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature. In the embodiment of FIG. 2 this means comprises means 105 acting in cooperation with motor valve 107, dewatering jet and necessary conduits. In the embodiment of FIG. 2 means 105 converts the third electrical signal into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber and comprises an Electro-Pneumatic Transducer, Type 546, manufactured by Fisher Control, Marshalltown, Iowa. Means 105 is powered by instrument air line 106 carrying air at some convenient pressure, such as 20 psi. The pneumatic signal is communicated to motor valve 107 by instrument air line 108. The magnitude of the pneumatic signal in air line 108 allows a quantity of air to flow through line 109 that is proportional to the magnitude, or pressure, of the pneumatic signal in line 108.

Dewatering jet 110 provides an apparatus by which the tow is caused to be displaced or deflected from its path and guided under dewatering jet 110 that is positioned at the downstream exit from and above heated water bath 12. The tow 10 is deflected around that por tion of the surface of dewatering jet 110 within which is the opening through which air is blown, the deflection being predominantly on the downstream side of the dewatering jet 110 with respect to the movement of the tow, and water is removed by blowing air from the opening of dewatering jet 110 against the surface of and through the tow so that most of the water is primarily blown upstream of the tow while other water is blown through the tow in return to the water bath. Dewatering jet 110 is a cylindrical hollow body member of predetermined length and is provided with a slot-like opening extending over a portion of the length of the body member and having substantially parallel walls and a depth to width ratio of about 5:1 and a radius on the outer lips of the opening of about one-thirty-second inch.

For reasons unknown to the inventors, it has been found that by positioning a dewatering jet device, which has a slot-like opening or slot having the depth to width ratio of 5:1, at the exit of the heated water bath where the tow has just emerged from the water, not only is a greater amount of water removed subsequently enabling the tow to be more effectively and uniformly heatset but also dewatering jet 1110 is not noisy and deafening to operating personnel and it is more economical to use because it requires less air consumption. It was found that the results were significantly different over those resulting from positioning the dewatering jet device farther downstream of the processing line where there was less water remaining on the tow. In the latter instance the dewatering jet device used more air, removed proportionately less water from the tow and was deafening to operating personnel with a decibel rating of about 103 dBA, as measured on the A scale of a standard sound level meter. On the other hand, the dewatering jet device at the exit of the heated water bath could not be detected against a background noise of about 90 to 92 dBA. Under the Occupational Noise Exposure section, U. S. Department of Labor Safety and Health Standards, Table I,

including correctiohs issued in .lul y l 969, W aIsh- Healey Regulation) the permissible noise exposure duration at 103 dBA for operating personnel is slightly over 1 hour but less than 1% hours per day. The permissible noise exposure for 90 to 92 dBA is from 8 to 6 hours per day, respectively.

The inventors have also found that a correlation can be established between temperature readings, taken for instance at the exit end of the heatsetting oven (not shown) and effective location, adjustment and angular orientation of the dewatering jet device. This assumes, of course, that other conditions on the tow processing line remain the same.

In using such temperature correlation inventors have discovered that for removing water the most effective position for the dewatering jet device is at the exit of the heated water bath; with the slot through which air is emitted being angularly oriented so that its axis or jet slot angle B, as measured from the upstream tangent point at the beginning of the wrapping engagement made by the tow with the jet device toward the downstream tangent point where the tow terminates contact with the jet device, extends from about 3 to about 8 with the wrap angle A extending correspondingly in the range of about 12 to about 40. It has also been discovered that when the dewatering jet device is pressed against the tow to deflect or displace the tow about one-half inch from its straight line path as it emerges from the heated water bath toward the first roll in a drafter roll section the most amount of water is removed. It has further been discovered, however, that by pressing the dewatering jet device still further against the tow until the extent of defection or displacement of the tow is about 1% inches, the least amount of air flow is used to achieve about the same amount of water removal as occurred at one-half inch displacement.

A more complete understanding of dewatering jet 110 can be obtained by considering several drawings.

FIG. 5 is an elevational view of a portion of a tow processing line showing a first drafter roll section, a heated water bath, the dewatering jet device at the exit of the tow from the heated water bath, followed by a second drafter roll section;

FIG. 6 is an enlarged elevational view of a portion of FIG. 5 in which may be seen water being removed in a fog or spray by the dewatering jet device;

FIG. 7 is an enlarged elevational view of a portion of FIG. 5 but illustrating an alternate arrangement wherein snubber bars are employed before and after the dewatering jet device;

FIG. 8 is a view of the dewatering jet device;

.(Federal Register, Volume 34, No. 96, May 20, 1969,

FIG. 9 is a cross-sectional view of the dewatering jet device taken along line 9-9 of FIG. 8;

FIG. 10 and 11 show, respectively, a graphic illustration of the jet slot angle relative to the tow wrap angle, and a graph illustrating the relationship of the two angles as to water removal efficiency;

FIG. 12 is a graph illustrating effect of tow displacement or deflection by dewatering jet device on water removal efficiency;

FIG. 13 is a graph illustrating effect of tow displacement or deflection by dewatering jet device on air flow rates and air pressure; and

FIG. 14 is a graph illustrating effect on tow temperature without a dewatering jet device, by a dewatering jet device located at the water bath, by a jet device located at the second drafter roll section, and by jet devices in tandem operation at both the water bath and the second drafter roll section.

Considering now the details of dewatering jet 110, in FIG. 5 the tow 10, a continuous length filamentary tow of synthetic fiber, such as polyester tow, enters a first drafter roll section 12 with the rolls 14 being driven at a predetermined rate of speed. The tow then enters a heated water bath indicated at 16 where the tow is heated to a predetermined temperature preparatory to being drafted by the second drafter roll section 18. The rolls 20 of the second drafter roll section are driven at a predetermined rate of speed greater than the rate of speed of the rolls of the first drafter roll section in order to draft the tow to a predetermined extent. The tow emerges from the heated water bath and passes under and into engagement with dewateringjet device 22 that is positioned at the exit of and above the heated water bath. The tow is displaced or deflected partly around and by the jet device from the path the tow would otherwise follow between the heated water bath and the first roll engaged by the tow on the second drafter roll section 18. Water is removed from the tow by the dewatering jet device to a predetermined extent preparatory to subsequent processing of the tow following the second drafter roll section. Such subsequent processing includes heat treating of the tow (not shown) in a manner well known in the art, such as illustrated in the aforementioned patents to I-lebeler and Patton et al.

The extent to which the dewatering jet device may be depressed against the tow may be dependent upon the spacing between the tow and the structure supporting the bath, and the location of the tow guide member 24 in the heated water bath relative to the location of the first roll in the second drafter roll section to be contacted by the tow. It may be desirable, especially if the tow is spaced relatively close to the heated water bath with insufficient space to obtain desired wrap angle, to aid the displacement of the tow by means of snubber bars 26 and 28 shown in an alternate arrangement (FIG. 7) in which the wrap angle A may be increased by depressing against the tow the dewatering jet device 22 between the snubber bars to a predetermined distance. An additional advantage derived from use of snubber bars to either side of the dewatering jet device is that some squeegee action occurs with water being removed from the underside surface of the tow. In the alternate arrangement of FIG. 7 components that are the same as that disclosed in FIGS. 5 and 6 have been identified by the same reference numbers which have prime marks beside them to distinguish the alternate arrangement from the arrangement disclosed in FIGS. and 6.

FIGS. 8 and 9 disclose in more detail the construction of the dewatering jet device 22 (FIGS. 5 and 6) or 22 (FIG. 7) which comprises a cylindrical body member 30 of a predetermined length and defining along its length an axially extending slot 32 of a length dependent upon the width of the tow to be treated. For reasons not entirely clear to inventors it has been found that effective water removal occurs when the depth of the slot in the cylindrical body member is about five times the width of the slot and with substantially parallel walls. This can readily be achieved by selecting cylindrical hollow bar stock meeting the following conditrons:

whereinR the inner radius of the body member; R the outer radius of the body member; and W= the width of the slot, as may be observed from FIG. 9. Another factor that appears to have some significance is the formation of a small radius 34 at each of the outer lips of the slot 32. If the radius is too small the lips will be too sharp and the tow will be damaged. In the instance of the particular body member 30 illustrated, with the outside diameter of the body member being about 1.312 inches, the small lip radius of the slot lips is about 1/32 inch or 0.031 inch, the slot width is about 1/16 inch or 0.062 inch and the depth of the slot is about 5/16 inch or 0.312 inch. It is thought that the air flow is straightened out more with this deep parallel wall slot construction and that the particularly small lip radius decreases Coanda flow around the lips for better air penetration of the tow and thus removes more water. In the operation of the dewatering jetdevice, the device may be suitably adjusted both in an annular orientation of the slot relative to the tow and depression against the tow by mechanical structure (not shown) that will support the device for such adjustments. The material from which the body member 30 is made is preferably a non-plucking, wear resistant material. For instance, the device illustrated is made of stainless steel and detonation coated such as by Union Carbide with their UCAR LA-2 (pure aluminum oxide) and lapped to a 20 rms (root mean square) microinch finish.

The purpose of the jet device is to remove the water that is held between the filaments in the tow band, and when this is done, and if done effectively, the tow will then present a smaller heat load to the heatset oven. The 'air emitted from the slot against the displaced tow is in effect compressed and in passing through the tow strips off the water held between the filaments. Some of the air will blow along the top of the tow stripping the water from the surface of the tow, while some air will pass entirely through the tow, but most of the air seems to penetrate into the tow and travel for a short distance between the filaments before emerging in the the slot is substantially sealed offwhen'the slotis about the center of the wrap angle so that little air is emitted.

As stated previously, with the discovery of being able to rely upon tow temperatures, such as might be taken at the exit of the heatset oven (not shown), it is possible to determine an effective location for the dewatering jet device, effective slot angular orientation, and effective tow displacement by depression of the dewatering jet device into the tow.

FIGS. 10 and 11 illustrate the relationship between tow wrap angle and jet slot angle with wrap angle being measured from the upstream tangent point 36, which is at the beginning of tow contact with the dewatering jet device, toward the downstream tangent point 38, which is where the tow moves out of contact with the jet device on its way to the second drafter roll section 18. The wrap angle is designed A; and the jet slot angle is designated B, which is measured from the upstream tangent point 36 toward the downstream tangent point 38 to the center or axis of the slot. In order to understand the significance of the graph shown in FIG. 11 it is necessary to correlate this with the other illustrated graphs that will be described herein.

The graph in FIG. 12 illustrates the effect of tow displacement on water removal in terms of temperature, and it may be observed that when the tow is displaced by the jet device about one-half inch, the maximum temperature results, with further tow displacements up to and including 1% inches resulting in approximately the same temperature as that with /2 inch displacement.

The graph in FIG. 13, however, illustrates the effect of tow displacement by the jet device on air flow rates and air pressure and shows that by increasing the displacement of the tow from one-half inch up to about 1% inches a more economical air flow in cubic feet per minute is achieved. It will thus be seen that increasing the tow displacement results in increased air pressure and decreased air flow.

In reference again to FIG. 11 when the tow is dis placed one-half inch the wrap angle A is about and the slot angle B is about 3; and when the tow displacement is about (1-%) inches the wrap angle A is about 40 and the slot angle B is about 8.

FIG. 14 shows the effect on heatset two temperature by comparing a dewatering jet device located at the heated water bath with a dewatering jet device located at the second drafter roll section, and in tandem operation with jet devices being located at the water bath and at 40 in the second drafter roll section, as shown in phantom lines in FIG. 1. It will readily be observed that when jet devices are operated in tandem, i.e., at two 10- cations at the same time, the water removal as shown by temperature increase is only slightly improved over the use of a dewatering jet device located at only the heated water bath; and that the use of the dewatering jet device at the heated water bath shows a significant improvement in terms of temperature over a situation where there is no dewatering jet device in operation. The graph further shows that when the measurements were repeated successively, as viewed from left to right, the two sets of results were fairly repeatable.

It has been found, therefore, that the particular location, adjustment and angular orientation, and the jet slot depth to width ratio of the dewatering jet device have produced unexpected results in terms of water removal efficiency, relative quiet operation and lower air consumption. The hollow conduit devices shown in the aforementioned Osban et al., U. S. Pat. No. 3,199,214, for instance, do not appear to recognize the criticalness of jet orifice size, angular orientation, and spacing of the hollow conduit devices from the water bath. Inventors cannot explain why the above described factors are proving to be effective; but can only offer some theories as speculated upon above. Dewatering jet devices placed at other locations along the tow processing line have not been found to be as significantly effective as the location described herein at the heated water bath. Similarly, the mere punching of holes or slots in hollow rods or conduits without giving any regard to size, shape and the like of such holes or slots has not appeared to be as significant as that described herein. The nature of this operation is such that can only be evaluated on an actual production line. It is for this reason that the actual noise made by the dewatering jet device at the water bath could not be detected over that of the operating tow lines. It is only known that by placing the dewatering jet device downstream at the second drafter roll section or at other locations resulted in a noise factor that could not be tolerated for any length of time by operating personnel, the noise was significantly noticeable; but at the water bath location whatever noise was made could not be picked up by the sound meter against the ambient background noise.

Dewatering jet 110 is described and claimed in our copending application Ser. No. 257,406, filed May 26, 1972, entitled Improved Method for Removing Water from Low and an improved Dewatering Jet for Practicing the Method.

Other means well known in the art and disclosed in U. S. Pat. No. 3,481,012 and U. S. Pat. No. 3,199,214 can be used to remove water from the wet fibers.

The process of this invention is applicable to the processing of numerous kinds of synthetic fibers, particularly polyesters, and more particularly poly(ethylene terephthalate).

While the invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

I. A method of controlling the processing ofa continuous length filamentary tow of synthetic fibers wherein the fibers are contacted with water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the wet drafted fibers are heatset, the method of controlling the processing comprising A. sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers.

B. comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and

C. responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature.

2. The method of claim 1 wherein water is removed from the wet fibers by positioning a horizontally extendingjet body member at the downstream exit from and above the heated water bath,

guiding the tow upon exit of the tow from the heated water bath immediately to and displacing it under and wrapping it partly around that portion of the surface of the jet body member wherein there is located an opening through which air is blown, and removing water from the fibers by blowing air through the opening against the wrapped around portion of the tow and toward the upstream portion of the tow and through the tow so that most of the water is primarily blown toward the upstream side of the tow while some water is blown through the tow in return to the heated water bath.

3. The method of claim 2 further including positioning a first horizontally extending snubber bar at the downstream exit from and above the heated water bath and immediately before the horizontally extending jet body member,

positioning a second horizontally extending snubber bar just after the jet body member, guiding the tow immediately from the water bath over the first snubber bar, under the jet body member and over the second snubber bar,

squeegeeing water from the tow by each of the first and second snubber bars, and

positioning the jet body member with respect to the first and second snubber bars so as to deflect the tow around the jet body member from a straight line path that the tow would otherwise follow between the first and second snubber bars.

4. The method of claim 3 further including wrapping the tow partly around the jet body member so that the angle of wrap from the upstream tangent point where the tow first engages the jet body member to the downstream tangent point where the tow moves out of engagement with the jet body member extends from about 12 to about 40, and the axis of thejet opening angle extends from about 3 to about 8, as measured from the upstream tangent point toward the downstream tangent point.

5. The method of claim 4 further including displacing the tow from a straight line path from the heated water bath by and in deflection around the jet body member from about inch to about 1% inches.

6. In the manufacture of a continuous length tow of high tenacity poly(ethylene terephthalate) fibers which have a dye take up inversely proportional to the temperature at which the fibers are heatset, the fibers are contacted with water, drafted and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the wet drafted fibers are heatset at constant length by heating the wet drafted fibers to an ultimate heatsetting temperature which is inversely proportional to the amount of water onthe wet fibers entering the heat-setting chamber, the invention which is a method for controlling the dye take up of the fibers by controlling the heatsetting temperature of the fibers through control of the amount of water on the wet drafted fibers entering the heatsetting chamber, the process comprising the steps of A. sensing the temperature of the fibers leaving the heatsetting chamber with a thermocouple and generating a first electrical signal having a voltage retinuous length filamentary tow of synthetic fibers wherein the fibers are contacted with water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber where the fibers are heatset, the apparatus for controlling the processing comprising flective of the magnitude of the sensed temperature,

B. converting the first electrical signal to a second electrical signal having an amperage reflective of the magnitude of the sensed temperature,

C. comparing the amperage of the second electrical signal with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a third electrical signal having an amperage reflective of the magnitude of the result of the comparison, and

D. converting the third electrical signal into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber,

responsive to the pneumatic signal, removing water from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature, the water being removed from the wet fibers by the steps of 1. positioning a first horizontally extending snubber bar at the downstream exit from and above the heated water bath,

2. positioning a horizontally extending jet body member at the downstream exitfrom and above the heated water bath and immediately after the first horizontal snubber bar,

3. positioning a second horizontally extending snubber bar just after the jet body member,

4. guiding the tow immediately from the water bath over the first snubber bar,

5. guiding the tow to and displacing it under and wrapping it around the jet body member so that the angle of wrap from the upstream tangent point where the tow first engages the jet body member to the downstream tangent point where the tow moves out of engagement with the jet body member extends from about 12 to about 40, and the axis of the jet opening angle extends from about 3 to about 8, as measured from the upstream tangent point toward the downstream tangent point,

6. guiding the tow over the second snubber bar,

7. squeegeeing water from the tow by each of the first and second snubber bars,

8. positioning the jet body member with respect to the first and second snubber bars so as to displace the tow from a straight line path from the heated water bath by and in deflection around the jet body member from about inch to about 1% inch, and

9. removing water from the fibers by blowing air through the opening against the wrapped around portion of the tow and toward the upstream portion of the tow and through the tow so that most of the water is primarily blown toward the upstream side of the tow while some water is blown through the tow in return to the heated water bath.

7. Apparatus for controlling the processing of a con- A. a means to sense the temperature of the fibers leaving the heatsetting chamber and generate a first signal reflective of the magnitude of the sensed temperature,

B. a means to compare the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generate a second signal reflective of the magnitude of the result of the comparison, and

C. a means utilizing the second signal to remove water from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature.

8. The apparatus of claim 7 wherein the means to remove water from the wet fibers entering the heatsetting chamber comprises a cylindrical hollow member of a predetermined length and defining through the wall of the member a slot-like opening extending over a portion of the length of the member.

9. The apparatus of claim 8 wherein the cylindrical hollow member defines a slot-like opening having substantially parallel walls and a depth to width ratio of about 5:1.

10. The apparatus of claim 9 wherein the width of the slot-like opening is about one-sixteenth inch, the depth of the slot-like opening is about five-sixteenth inch, and the radius on the outer lips of the opening is about onethirty-second inch.

1 1. Apparatus for controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the fibers are contacted with water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the fibers are heatset, the apparatus for controlling the processing comprising A. a thermocouple to sense the temperature of the fibers leaving the heatsetting chamber and generate a first electrical signal having a voltage reflective of the magnitude of the sensed temperature,

B. a means to convert the first electrical signal to a second electrical signal having an amperage reflective of the magnitude of the sensed temperature,

C. a means to compare the amperage of the second electrical signal with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and generate a third electrical signal having an amperage reflective of the magnitude of the result of the comparison,

D. a means to convert the third electrical signal into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber,

E. a means communicating with the pneumatic signal to remove water from the wet fibers entering the heatsetting chamber, the means comprising a cylindrical hollow member of predetermined length and defining through the wall of the member a slot-like opening extending over a portion of the length of the member, the slot-like opening having a width of about one-sixteenth inch, a depth of about fivesixteenth inch, a depth to width ratio of about 5:1 and a radius on the outer lips of the opening of about one-thirty-second inch. 

1. A method of controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the fibers are contacted wIth water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the wet drafted fibers are heatset, the method of controlling the processing comprising A. sensing the temperature of the fibers leaving the heatsetting chamber and generating a first signal reflective of the magnitude of the sensed temperature of the fibers. B. comparing the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a second signal reflective of the magnitude of the result of the comparison, and C. responsive to the second signal, removing water from the wet fibers entering the heatsetting chamber to allow the fibers to achieve the desired temperature.
 2. The method of claim 1 wherein water is removed from the wet fibers by positioning a horizontally extending jet body member at the downstream exit from and above the heated water bath, guiding the tow upon exit of the tow from the heated water bath immediately to and displacing it under and wrapping it partly around that portion of the surface of the jet body member wherein there is located an opening through which air is blown, and removing water from the fibers by blowing air through the opening against the wrapped around portion of the tow and toward the upstream portion of the tow and through the tow so that most of the water is primarily blown toward the upstream side of the tow while some water is blown through the tow in return to the heated water bath.
 2. positioning a horizontally extending jet body member at the downstream exit from and above the heated water bath and immediately after the first horizontal snubber bar,
 3. positioning a second horizontally extending snubber bar just after the jet body member,
 3. The method of claim 2 further including positioning a first horizontally extending snubber bar at the downstream exit from and above the heated water bath and immediately before the horizontally extending jet body member, positioning a second horizontally extending snubber bar just after the jet body member, guiding the tow immediately from the water bath over the first snubber bar, under the jet body member and over the second snubber bar, squeegeeing water from the tow by each of the first and second snubber bars, and positioning the jet body member with respect to the first and second snubber bars so as to deflect the tow around the jet body member from a straight line path that the tow would otherwise follow between the first and second snubber bars.
 4. guiding the tow immediately from the water bath over the first snubber bar,
 4. The method of claim 3 further including wrapping the tow partly around the jet body member so that the angle of wrap from the upstream tangent point where the tow first engages the jet body member to the downstream tangent point where the tow moves out of engagement with the jet body member extends from about 12* to about 40*, and the axis of the jet opening angle extends from about 3* to about 8*, as measured from the upstream tangent point toward the downstream tangent point.
 5. The method of claim 4 further including displacing the tow from a straight line path from the heated water bath by and in deflection around the jet body member from about 1/2 inch to about 1 1/4 inches.
 5. guiding the tow to and displacing it under and wrapping it around the jet body member so that the angle of wrap from the upstream tangent point where the tow first engages the jet body member to the downstream tangent point where the tow moves out of engagement with the jet body member extends from about 12* to about 40*, and the axis of the jet opening angle extends from about 3* to about 8*, as measured from the upstream tangent point toward the downstream tangent point,
 6. guiding the tow over the second snubber bar,
 6. In the manufacture of a continuous length tow of high tenacity poly(ethylene terephthalate) fibers which have a dye take up inversely proportional to the temperature at which the fibers are heatset, the fibers are contacted with water, drafted and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the wet drafted fibers are heatset at constant length by heating the wet drafted fibers to an ultimate heatsetting temperature which is inversely proportional to the amount of water on the wet fibers entering the heat-setting chamber, the invention which is a method for controlling the dye take up of the fibers by controlling the heatsetting temperature of the fibers through control of the amount of water on the wet drafted fibers entering the heatsetting chamber, the process comprising the steps of A. sensing the temperature of the fibers leaving the heatsetting chamber with a therMocouple and generating a first electrical signal having a voltage reflective of the magnitude of the sensed temperature, B. converting the first electrical signal to a second electrical signal having an amperage reflective of the magnitude of the sensed temperature, C. comparing the amperage of the second electrical signal with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and generating a third electrical signal having an amperage reflective of the magnitude of the result of the comparison, and D. converting the third electrical signal into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber, E. responsive to the pneumatic signal, removing water from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature, the water being removed from the wet fibers by the steps of
 7. Apparatus for controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the fibers are contacted with water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber where the fibers are heatset, the apparatus for controlling the processing comprising A. a means to sense the temperature of the fibers leaving the heatsetting chamber and generate a first signal reflective of the magnitude of the sensed temperature, B. a means to compare the first signal with a signal reflective of a desired temperature for the fibers leaving the heatsetting chamber and generate a second signal reflective of the magnitude of the result of the comparison, and C. a means utilizing the second signal to remove water from the wet fibers entering the heatsetting chamber so as to allow the fibers to achieve the desired temperature.
 7. squeegeeing water from the tow by each of the first and second snubber bars,
 8. positioning the jet body member with respect to the first and second snubber bars so as to displace the tow from a straight line path from the heated water bath by and in deflection around the jet body member from about 1/2 inch to about 1 1/4 inch, and
 8. The apparatus of claim 7 wherein the means to remove water from the wet fibers entering the heatsetting chamber comprises a cylindrical hollow member of a predetermined length and defining through the wall of the member a slot-like opening extending over a portion of the length of the member.
 9. The apparatus of claim 8 wherein the cylindrical hollow member defines a slot-like opening having substantially parallel walls and a depth to width ratio of about 5:1.
 9. removing water from the fibers by blowing air through the opening against the wrapped around portion of the tow and toward the upstream portion of the tow and through the tow so that most of the water is primarily blown toward the upstream side of the tow while some water is blown through the tow in return to the heated water bath.
 10. The apparatus of claim 9 wherein the width of the slot-like opening is about one-sixteenth inch, the depth of the slot-like opening is about five-sixteenth inch, and the radius on the outer lips of the opening is about one-thirty-second inch.
 11. Apparatus for controlling the processing of a continuous length filamentary tow of synthetic fibers wherein the fibers are contacted with water, drafted, and subsequently the wet drafted fibers are conducted into a heatsetting chamber wherein the fibers are heatset, the apparatus for controlling the processing comprising A. a thermocouple to sense the temperature of the fibers leaving the heatsetting chamber and generate a first electrical signal having a voltage reflective of the magnitude of the sensed temperature, B. a means to convert the first electrical signal to a second electrical signal having an amperage reflective of the magnitude of the sensed temperature, C. a means to compare the amperage of the second electrical signal with an amperage reflective of a desired temperature for the fibers leaving the heatsetting chamber and generate a third electrical signal having an amperage reflective of the magnitude of the result of the comparison, D. a means to convert the third electrical signal into a pneumatic signal having a magnitude reflective of the sensed temperature of the fiber, E. a means communicating with the pneumatic signal to remove water from the wet fibers entering the heatsetting chamber, the means comprising a cylindrical hollow member of predetermined length and defining through the wall of the member a slot-like opening extending over a portion of the length of the member, the slot-like opening having a width of about one-sixteenth inch, a depth of about five-sixteenth inch, a depth to width ratio of about 5:1 and a radius on the outer lips of the opening of about one-thirty-second inch. 